CN101093319A

CN101093319A - Surface light source device and liquid crystal display unit

Info

Publication number: CN101093319A
Application number: CNA2007101280067A
Authority: CN
Inventors: 青木富雄; 林正健; 增田昌三; 森本忠司
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2006-06-21
Filing date: 2007-06-20
Publication date: 2007-12-26
Anticipated expiration: 2027-06-20
Also published as: EP1873578B1; CN100541293C; KR101425956B1; US7658529B2; TW200811547A; EP1873578A1; JP4857945B2; US20080123022A1; US20100033649A1; JP2008003220A; US20200234661A1; EP2264520A3; EP2264520B1; KR20070121528A; US10650756B2; TWI375082B; US10923050B2; EP2264520A2

Abstract

A surface light source device which illuminates a transmission-type liquid crystal display unit from the back surface includes PxQ surface light source units with individually controlled light sources. Each of the light sources includes a plurality of light-emitting element units. Each of the light-emitting element units includes at least one red light-emitting element that emits red light, at least one green light-emitting element that emits green light, and at least one blue light-emitting element that emits blue light. The center of mass of a luminance profile based on each of a plurality of red light-emitting elements, a plurality of green light-emitting elements, and a plurality of blue light-emitting elements in each surface light source unit substantially coincides with the center of mass of the surface light source unit.

Description

Planar light source device and liquid crystal display

The cross reference of related application

The present invention comprises the Japanese patent application laid of submitting in the Japan special permission Room with on June 21st, 2006 and is willing to the subject content that 2006-17139 is relevant, and its former content quoted is contained in this.

Technical field

The present invention relates to a kind of planar light source device and liquid crystal display.

Background technology

In liquid crystal display, liquid crystal itself is not luminous.Therefore, for example the so-called directly profile light supply apparatus (backlight) of irradiate light to the viewing area of liquid crystal display is set on the back side of the viewing area that is made of a plurality of pixels.Should be noted that in color liquid crystal display unit a pixel is made of three sub-pixels that comprise emitting red light sub-pixel, green emitting sub-pixel and blue-light-emitting sub-pixel.Work as a kind of optical gate (light valve) by making the liquid crystal cells that constitutes each pixel or sub-pixel, promptly the transmittance by control each pixel or sub-pixel (aperture than) is controlled the transmittance of the illumination light of sending from planar light source device (for example white light), shows an image thus.

In the prior art, the planar light source device of liquid crystal display subassembly illuminates whole viewing area with homogeneous and constant brightness.Existing known to opening disclosed a kind of planar light source device in the 2005-258403 communique with structure different with above-mentioned planar light source device the Japanese Unexamined Patent Application spy, planar light source device in the document comprises a plurality of surface light source units, and the Illumination Distribution in the unit, a plurality of viewing area is changed.

This planar light source device is based on following method Be Controlled.That is, the maximum briliancy that constitutes each surface light source unit of this planar light source device is given as Y _Max, and the maximal value of the transmittance of the pixel in the unit, viewing area (aperture than) (specifically, for example 100%) is given as Lt _MaxIn addition, each surface light source unit when this planar light source device of formation has maximum briliancy Y _MaxThe time, each pixel obtains to show briliancy y in the unit, viewing area ₀The transmittance of each required pixel (aperture ratio) is given as Lt ₀Thus, in this case, may command constitutes the light source briliancy Y of each surface light source unit of this planar light source device ₀To satisfy following relation.

Y ₀·Lt _max＝Y _max·Lt ₀。

The conceptual illustration of this control provides in Figure 11 A and Figure 11 B.In this case, each frame (being referred to as image display frame for ease of explanation) in the image demonstration of liquid crystal display is changed the light source briliancy Y of surface light source unit ₀

To the control (often being referred to as the division driving of planar light source device) of planar light source device,, therefore can realize the raising of contrast by as mentioned above because whiteness raises and the blackness reduction in the liquid crystal display.As a result, can realize the raising of image displaying quality, and reduce the power consumption of planar light source device.

Open in the disclosed technology of 2005-258403 communique the Japanese Unexamined Patent Application spy, four light emitting diodes (LED) (opening 2005-258403 communique [0071] section and Figure 18 referring to the Japanese Unexamined Patent Application spy) are set in a surface light source unit.Japanese Unexamined Patent Application spy opens that being configured among Figure 12 of disclosed four LED schematically illustrated in the 2005-258403 communique.

In addition, example illustrates a part that illuminates the configuration of the light emitting diode in the planar light source device of whole viewing area with homogeneous and constant brightness among Figure 13 A and Figure 14 A.An example of this configuration is in 124 to 128 pages of No. the 889th, the Nikkei electrons on Dec 20th, 2004.Here, in the accompanying drawings, red light emitting diodes is by the mark indication that is included in the letter " R " in the circle, and green LED is by the mark indication that is included in the letter " G " in the circle, and blue LED is by the mark indication that is included in the letter " B " in the circle.

Summary of the invention

In the configuration of four LED shown in Figure 12 A, as in the rim area of Figure 12 surface light source unit that B is shown in local luminous aberration (luminous colour cast) taking place.That is, when the middle body from surface light source unit penetrates white light, slightly be different from the coloured light of white from the rim area ejaculation of surface light source unit.Should be noted that in Figure 12 B the choice refreshments line is schematically indicated the level line of set-point in the briliancy distribution that is produced by blue-light-emitting LED.In addition, dot-and-dash line schematically illustrates the level line of the set-point in the briliancy distribution that is produced by emitting red light LED.Although omitted the level line of the set-point of the briliancy that is produced by green emitting LED in distributing among the figure, yet these level lines distribute with the briliancy that is produced by emitting red light LED or the level line that distributed by the briliancy that green emitting LED produces is inconsistent.

Equally, in the situation that the separation based on the LED configuration attempt planar light source device shown in Figure 13 A and the 14A drives, local luminous aberration (luminous colour cast) will take place like that shown in Figure 13 B or 14B.In Figure 13 A and Figure 14 A, the cutting state of solid line indication planar light source device when attempting the division driving planar light source device.In addition, in Figure 13 B and 14B, the part that the solid line indication is corresponding with the outer rim of surface light source unit.

This local aberration (colour cast) in the surface light source unit outer edge area causes in the pixel of the liquid crystal display corresponding with the outer edge area of surface light source unit the deviation with want color.

Therefore be desirable to provide a kind of planar light source device, this planar light source device has makes configuration and the structure that is not easy to take place local aberration (colour cast) in formation is accepted the outer edge area of surface light source unit of planar light source device of division driving.

According to of the present invention first to the third aspect, a kind of planar light source device that illuminates the transmission-type liquid crystal display unit with the viewing area that comprises the pixel of arranging with two-dimensional matrix from the back side is provided here, and described planar light source device comprises: be divided into P * Q P * Q the corresponding surface light source unit of imaginary display unit that P * Q unit, imaginary viewing area obtains with the viewing area by the hypothesis liquid crystal display.All light sources included in the surface light source unit are controlled individually, included light source comprises a plurality of light-emitting device unit in each surface light source unit, and each light-emitting device unit comprises the green luminousing element of at least one red light-emitting component that glows, at least one green light and the blue light emitting device of at least one blue light-emitting.

In addition, in planar light source device according to first aspect present invention, the center of gravity that distributes based on the briliancy of a plurality of red light-emitting components in each surface light source unit is consistent with the center of gravity of surface light source unit, the center of gravity and the center of gravity basically identical of surface light source unit that distribute based on the briliancy of a plurality of green luminousing elements in each surface light source unit, and based on the center of gravity of the briliancy distribution of a plurality of blue light emitting devices in each surface light source unit and the center of gravity basically identical of surface light source unit.

Here, the state of the center of gravity basically identical of the center of gravity that distributes based on the briliancy of a plurality of red light-emitting components in the surface light source unit and this surface light source unit is prescribed as follows.Promptly, in planar light source device, in a surface light source unit, have only a plurality of red light-emitting components to be lighted distributing, and determine that this two dimension briliancy is included in the center of gravity of the part in the projected image of outer rim of this surface light source unit in distributing based on the photo measure that sends from these a plurality of red light-emitting components two dimension briliancy.Then, if the center of gravity (it is general consistent with the central point of surface light source unit) that the centre of gravity place that this briliancy distributes is positioned at surface light source unit is that the diameter that draws in the center is the circle of D (mm), then think the center of gravity " basically identical " each other of the center of gravity of this briliancy distribution and surface light source unit.Here, if the surface area of surface light source unit is taken as S ₀(mm ²), then the value of " D " (unit: mm) satisfy following relation:

D＝0.2 S ₀ ^1/2

Same definition also is applicable to the state of " center of gravity and the center of gravity basically identical of surface light source unit that distribute based on the briliancy of a plurality of green luminousing elements in each surface light source unit " or " based on the center of gravity of the briliancy distribution of a plurality of blue light emitting devices in each surface light source unit and the center of gravity basically identical of surface light source unit ".Should be noted that and initial point (0,0) ought be arranged in the precalculated position in the briliancy distribution, and the point (x in briliancy distributes _i, y _i) briliancy be given as L (x _i, y _i) time, (Xc Yc) can be by determining with following formula (A) with (B) for the coordinate of the center of gravity that briliancy distributes.

X_{c} = \frac{\underset{i}{Σ} \underset{j}{Σ} x_{i} L (x_{i}, y_{j})}{\underset{i}{Σ} \underset{j}{Σ} L (x_{i}, y_{j})} - - - (A)

Y_{c} = \frac{\underset{i}{Σ} \underset{j}{Σ} y_{i} L (x_{i}, y_{j})}{\underset{i}{Σ} \underset{j}{Σ} L (x_{i}, y_{j})} - - - (B)

In addition, in planar light source device according to a second aspect of the invention, the center of gravity basically identical of the center of gravity of the position of a plurality of red light-emitting components in each surface light source unit and surface light source unit, the center of gravity basically identical of the center of gravity of the position of a plurality of green luminousing elements in each surface light source unit and surface light source unit, and the center of gravity basically identical of the center of gravity of the position of a plurality of blue light emitting devices in each surface light source unit and surface light source unit.

Here, when the center of gravity basically identical of the center of gravity of the position of a plurality of red light-emitting components in the surface light source unit and this surface light source unit, this means if the surface area of surface light source unit is taken as S ₀(mm ²), then concern below the satisfying of the center of gravity (consistent with the central point of planar light source device usually) from the center of gravity of the position of these a plurality of red light-emitting components (centers of gravity of these a plurality of red light-emitting components of determining according to the position coordinates of these a plurality of red light-emitting components) to surface light source unit apart from d.Same definition also is applicable to a plurality of green luminousing elements and a plurality of blue light emitting device.

d≤0.05S ₀ ^1/2

In addition, in planar light source device according to third aspect present invention, surface light source unit is rectangle in planimetric map, and in each surface light source unit, each limit along surface light source unit is provided with at least one red light-emitting component, at least one green luminousing element and at least one blue light emitting device, and this red light-emitting component, green luminousing element and blue light emitting device are to arrange with same sequence along four limits of surface light source unit.

Note, in planar light source device according to third aspect present invention, when the one side along surface light source unit is provided with a plurality of red light-emitting components and/or a plurality of green luminousing element and/or a plurality of blue light emitting device, preferably the light-emitting component of same color is not arranged adjacent to each other.In addition, when when the limit of two adjacent surface light source units is observed, preferably make putting in order of these red light-emitting components, green luminousing element and blue light emitting device identical.

In first the planar light source device (hereinafter it being referred to as planar light source device according to an embodiment of the invention), be included in a light source in the surface light source unit and comprise a plurality of light-emitting device unit to the third aspect according to the present invention.Specifically, the quantity of light-emitting device unit is just enough greater than 2.In this case, each red light-emitting component that preferably will constitute these a plurality of light-emitting device unit is arranged to secondary rotation symmetry, each green luminousing element that constitutes these a plurality of light-emitting device unit is arranged to secondary rotation symmetry, and each blue light emitting device that will constitute these a plurality of light-emitting device unit to be arranged to the secondary rotation symmetrical.In addition, optimally, the number of light-emitting component is 4.

In addition, when being included in a light source in the surface light source unit and comprising four light-emitting device unit, preferably in each surface light source unit, each red light-emitting component that constitutes these four light-emitting device unit is arranged to the rotation symmetry four times, each green luminousing element that constitutes these four light-emitting device unit is arranged to the rotation symmetry four times, and each blue light emitting device that will constitute these four light-emitting device unit to be arranged to four rotations symmetrical.In addition, in this case, wish that each light-emitting device unit comprises a red light-emitting component, two green luminousing elements and a blue light emitting device, these four light-emitting components are set on four jiaos of hypothetical rectangle, and when hypothesis one initial point is located at the coordinate system of center of gravity of surface light source unit rectangular in the planimetric map, green luminousing element is set at of being arranged in the most close initial point in four jiaos of hypothetical rectangle and hypothetical rectangle four jiaos respectively and is positioned at farthest from a place of initial point, and red light-emitting component and blue light emitting device are separately positioned on remaining two jiaos places.Perhaps, in this case, wish that each light-emitting device unit comprises a red light-emitting component, a green luminousing element and a blue light emitting device, and these three light-emitting components are separately positioned on the distal portion and the intersection point place between straight thick stick and whippletree of whippletree of distal portion, this imagination letter " L " of the straight thick stick of imagination letter " L ".Perhaps, also can adopt a kind of like this configuration, wherein each light-emitting device unit comprises a red light-emitting component, two green luminousing elements and a blue light emitting device, and when the one group of unit that is provided with as described above was called as " Unit 2 * 2 ", each light-emitting device unit comprised 1 * 2=2 " Unit 2 * 2 " or 2 * 2=4 " Unit 2 * 2 " or 2 * 3=6 " Unit 2 * 2 " or a * b=ab " Unit 2 * 2 ".

In the planar light source device according to an embodiment of the invention that comprises various as mentioned above preference patterns and configuration, per two adjacent surface light source units can be separated each other by partition wall.Because partition wall, optical transmission, reflection or the transmission of sending from the light source that constitutes surface light source unit with reflect Be Controlled.Be noted that in this case a surface light source unit is surrounded by four partition walls, perhaps a side by three partition walls and housing surrounds (this will describe after a while), and perhaps two sides by two sidewalls and housing surround.The examples of material that constitutes partition wall comprises acryl resin, polycarbonate resin and ABS resin.The surface of partition wall can be endowed light diffuse reflection function or direct reflection function.Can be by irregularly shapedly maybe having erose film (light-diffusing film) and be attached to and give partition wall surface light diffuse reflection function on the partition wall surface forming on the partition wall surface based on sand-blast.In addition, can be by optical reflection film being attached on the partition wall surface or on the surface of partition wall, forming reflection layer and will give partition wall surface minute surface reflection function by for example electroplating.

In comprising the planar light source device according to an embodiment of the invention of various preferred disposition as mentioned above, can be with light emitting diode (LED) as light-emitting component.In the situation that light-emitting component is formed by light emitting diode, for example sending, the red light emitting diodes of the ruddiness of 640nm wavelength can be used as red light-emitting component, for example send that the green LED of the green glow of 530nm wavelength can be used as green luminousing element, the blue LED of the blue light of 450nm wavelength can be used as blue light emitting device and for example send.White light can be by being achieved from these lumination of light emitting diode.Although the light of sending out the 4th look except that red, green, blue and the light of the five colors can further be provided ... light-emitting component (light emitting diode), yet in this case, send the 4th coloured light and multicolored light ... light-emitting component need satisfy the desired regulation of red light-emitting component, green luminousing element and blue light emitting device equally.

Light emitting diode can have so-called structure or the upside-down mounting slice structure of facing up.That is, can adopt light emitting diode wherein by substrate be formed on that luminescent layer on the substrate constitutes and light is transmitted to outside structure from luminescent layer, maybe can adopt wherein light to be transmitted to outside structure by substrate from luminescent layer.More particularly, light emitting diode (LED) has: comprise first coating that is formed on the substrate and is made of the compound semiconductor layer with first conduction type (for example n type); Second coating that is formed on the active layer on first coating and is formed on first coating and constitutes by compound semiconductor layer with second conduction type (for example p type), and comprise first electrode that is electrically connected in first coating and second electrode that is electrically connected in second coating.The layer that constitutes light emitting diode can be made of the known compound semiconductor material according to emission wavelength.

Should be noted that the lens that have highlight strength on the craspedodrome direction can be installed in the luminous component of light emitting diode in lambert (Lambert) cyan type.

In planar light source device according to an embodiment of the invention, be desirable to provide a kind of optical sensor that is used for the luminance (specifically, the briliancy of the colourity of the briliancy of light source, light source or light source and colourity) of measurement light source.Although the number of optical sensor can be at least one,, close and need for each surface light source unit is provided with one group of optical sensor from the angle of the luminance of measuring each surface light source unit reliably.Known photodiode or CCD device can be used as optical sensor.In addition in this case, one group of optical sensor can be by being connected with the photodiode of red color filter with the light intensity of measuring ruddiness, being connected with green color filter with the photodiode of the light intensity of measuring green glow and be connected with blue color filter and constitute with the photodiode of the light intensity of measuring blue light.

Here, briliancy (demonstration briliancy) y at the part place corresponding with this pixel or sub-pixel and briliancy (light source briliancy) Y of surface light source unit are defined as follows in the transmittance of pixel or sub-pixel (being also referred to as the aperture ratio) Lt, the viewing area:

Y ₁: the light source briliancy, for example its maximal value often is called as the first regulation light source brightness value hereinafter.

Lt ₁: the pixel in the unit, viewing area or the transmittance of sub-pixel (aperture ratio), for example its maximal value often is called as the first regulation light transmittance values hereinafter.

Lt ₂: by hypothesis with have maximum drive signal value x in the unit, peaked viewing area that equals to represent the drive signal value that is input to the driving circuit that is used to drive all pixels that constitute the unit, viewing area _U-maxThe control signal of drive signal correspondence of value be provided for pixel or sub-pixel and the transmittance of this pixel that obtains or sub-pixel (aperture than).Hereinafter often be referred to as the second regulation light transmittance values.It should be noted that 0≤Lt ₂≤ Lt ₁

y ₂: by hypothesis light source briliancy is that the transmittance (aperture than) of the first regulation light source brightness value Y1 and pixel or sub-pixel is the demonstration briliancy that the second regulation light transmittance values Lt2 obtains.Hereinafter, this often is called as second regulation and shows brightness value.

Y ₂: the hypothesis with have with the unit, viewing area in maximum drive signal value X _U-maxThe control signal of the drive signal correspondence of the value that equates has been provided for pixel or sub-pixel and has further supposed this pixel or be corrected to the first regulation light transmittance values Lt to the transmittance of sub-pixel (aperture than) ₁Situation under, the briliancy that makes this pixel or sub-pixel is that second regulation shows brightness value (y ₂) the light source briliancy of required surface light source unit.Yet, be noted that to have light source briliancy Y ₂Be subjected to considering the situation of the light source briliancy of each surface light source unit to the correction of the influence of the light source transmissivity of other surface light source unit.

In the driving process of planar light source device according to an embodiment of the invention, the briliancy that constitutes the light source of the surface light source unit corresponding with the unit, viewing area is controlled to obtain by hypothesis and to have the maximum drive signal value X that equals in the unit, viewing area by driving circuit _U-maxThe control signal of drive signal correspondence of value be provided for this pixel or sub-pixel and the pixel briliancy that obtains (at the first regulation light transmittance values Lt ₁Under second regulation show brightness value y ₂).Specifically, may command light source briliancy Y for example ₂(for example reducing) is set at the first regulation light transmittance values Lt with the transmittance (aperture ratio) at pixel or sub-pixel ₁The time to show briliancy y ₂That is, for example can be to the light source briliancy Y of each image display frame chain of command light source cell ₂To satisfy with following formula (1), wherein Y ₂≤ Y ₁

Y ₂·Lt ₁＝Y ₁·Lt ₂ (1)

Driving circuit can comprise for example by the area source control circuit (backlight control unit and surface light source unit driving circuit) of formations such as width modulation (PWM) signal generating circuit, control circuit of duty ratio, light emitting diode (LED) driving circuit, computing circuit, storer and the liquid crystal display driving circuit that is made of the known circuit such as time schedule controller.

This planar light source device also further comprises the optical function sheet group with diffusion sheet, prismatic lens and polarisation transformation sheet or reflector plate.

The transmission-type liquid crystal display unit for example comprises: the front panel with first transparency electrode; Have the rear panel of second transparency electrode and be set at front panel and rear panel between liquid crystal material.

More particularly, front panel for example comprises: first substrate of being made by glass substrate or silicon substrate; Be arranged on first transparency electrode (be also referred to as public electrode, and form) on the first substrate inside surface and be arranged on polarizing coating on first outer surface of substrate by for example ITO.In addition, in the situation of transmission type colour liquid crystal display unit, the color filter that scribbles the coating of being made by acryl resin or epoxy resin is set on the inside surface of first substrate.The example of pattern of rows and columns of color filter comprises △ arrangement, stripe-arrangement, diagonal angle arrangement and rectangular arranged.In addition, front panel has the structure that wherein further forms first transparency electrode on coating.On the other hand, more particularly, rear panel for example comprises: second substrate of being made by glass substrate or silicon substrate; Be formed on the on-off element on the second substrate inside surface; Control second transparency electrode (be also referred to as pixel electrode, and for example make) of its conducting/not conducting by ITO by on-off element; And be arranged on polarizing coating on second outer surface of substrate.Comprising formation one oriented layer on the whole surface of second transparency electrode.These parts and liquid crystal materials that constitute the transmission type colour liquid crystal display unit can be made of known elements and material.The example of on-off element comprise be formed on the monocrystalline silicon semiconductor substrate such as MOS type FET or thin film transistor (TFT) three-terminal elements such as (TFT) or such as two-terminal elements such as MIM element, varistor element or diodes.

Overlapping and the zone that comprises liquid crystal cells of first transparency electrode and second transparency electrode is corresponding to a pixel or a sub-pixel.In addition, in the transmission type colour liquid crystal display unit, the emitting red light sub-pixel (sub-pixel [R]) that constitutes each pixel is constituted by above-mentioned zone and the color filter that sees through red light, green emitting sub-pixel (sub-pixel [G]) is constituted by above-mentioned zone and the color filter that sees through green light, and blue-light-emitting sub-pixel (sub-pixel [B]) constituting by above-mentioned zone and the color filter that sees through blue light.Sub-pixel [R], sub-pixel [G] are identical with the arrangement mode of above-mentioned color filter with the arrangement mode of sub-pixel [B].Be noted that pixel not necessarily is made of one group of three sub-pixel that comprises emitting red light sub-pixel, green emitting sub-pixel and blue-light-emitting sub-pixel.Also can (for example constitute a pixel by the one group of sub-pixel that outside these three sub-pixels, adds one or more sub-pixels in addition, added the one group of sub-pixel that emits white light with the sub-pixel that improves briliancy, added and sent the one group sub-pixel of complementary color light with the sub-pixel of increase color reproduction scope, added and sent the one group sub-pixel of gold-tinted with the sub-pixel that increases the color reproduction scope, and added send gold-tinted and blue or green light one group of sub-pixel with the sub-pixel that increases the color reproduction scope).

Number M when the pixel of arranging with two-dimensional matrix ₀* N ₀With (M ₀, N ₀) when form provides, for example VGA (640,480), S-VGA (800,600), XGA (1024,768), APRC (1152,900), S-XGA (1280,1024), U-XGA (1600,1200), HD-TV (1920,1080) and Q-XGA (2048,1536), also have (1920,1035), (720,480), (1280,960) wait several image display resolutions to can be used as (M ₀, N ₀) the example of particular value.Yet, value (M ₀, N ₀) be not limited to these values.Although at (M ₀, N ₀) value and (P, there is not restriction in the relation between value Q), yet this relation can be illustrated as shown in the following table 1 like that.The scope of number that constitutes the pixel of unit, a viewing area can from 20 * 20 to 320 * 240, are more preferably from 50 * 50 to 200 * 200.The number of the pixel in the unit, viewing area can be fixing or change.

Table 1

	The P value	The Q value
	The P value	The Q value	VGA(640，480)	2～32	2～24
S-VGA(800，600)	3～40	2～30	VGA(640，480)	2～32	2～24
S-VGA(800，600)	3～40	2～30	XGA(1024，768)	4～50	3～39
APRC(1152，900)	4～58	3～45	XGA(1024，768)	4～50	3～39
APRC(1152，900)	4～58	3～45	S-XGA(1280，1024)	4～64	4～51
U-XGA(1600，1200)	6～80	4～60	S-XGA(1280，1024)	4～64	4～51
U-XGA(1600，1200)	6～80	4～60	HD-TV(1920，1080)	6～86	4～54
Q-XGA(2048，1536)	7～102	5～77	HD-TV(1920，1080)	6～86	4～54
Q-XGA(2048，1536)	7～102	5～77	(1920，1035)	7～64	4～52
(720，480)	3～34	2～24	(1920，1035)	7～64	4～52
(720，480)	3～34	2～24	(1280，960)	4～64	3～48

In planar light source device according to an embodiment of the invention, by stipulating based on a plurality of red light-emitting components in each surface light source unit, relation between the center of gravity that the briliancy of green luminousing element and blue light emitting device distributes and the center of gravity of surface light source unit, or by stipulating a plurality of red light-emitting components in each surface light source unit, relation between the center of gravity of the position of green luminousing element and blue light emitting device and the center of gravity of surface light source unit, or by stipulating a plurality of red light-emitting components in each surface light source unit, layout/the arrangement of green luminousing element and blue light emitting device can prevent to take place local aberration (colour cast) reliably in the outer edge area of surface light source unit.As a result, can suppress the generation that departs from of the color of wanting in the pixel of the liquid crystal display corresponding with the outer edge area of surface light source unit.

In the situation that all surface light source units are separated each other by partition wall in planar light source device, because the existence of partition wall, local aberration (colour cast) becomes more obvious in the outer edge area of surface light source unit.Given this, use planar light source device according to an embodiment of the invention, can prevent the generation of local aberration (colour cast) in the rim area of surface light source unit reliably, even therefore when surface light source unit is separate by partition wall, also unlikely going wrong.

In addition, in planar light source device according to an embodiment of the invention, when the briliancy of the light source that constitutes the surface light source unit corresponding with unit, a viewing area is controlled to obtain by hypothesis and has the maximum drive signal value x that equals in the unit, viewing area _U-maxThe control signal of drive signal correspondence of value be provided for pixel and the pixel briliancy that obtains (at the first regulation light transmittance values Lt ₁Under second regulation show brightness value y ₂) time, not only can realize the reduction of the power consumption of surface light source unit, can also realize that whiteness improves or the reduction of blackness, realize that thus high-contrast is (on the screen surface of liquid crystal display, do not containing under the situation of external light reflection etc., full the ratio of the briliancy of the briliancy of black display part and complete white display part).Because thereby can improve the brightness of desired viewing area, therefore can realize the raising of image displaying quality.

Description of drawings

Figure 1A and 1B are the synoptic diagram that schematically illustrates according to the configuration of the formation light-emitting component of embodiment 1;

Fig. 2 A and 2B are the synoptic diagram that schematically illustrates according to the configuration of the formation light-emitting component of embodiment 2;

Fig. 3 is the curve map that an example of briliancy distribution schematically is shown;

Fig. 4 is the process flow diagram that illustrates according to the method for the driving liquid crystal display of embodiment 1;

Fig. 5 comprises the concept map that is applicable to the liquid crystal display subassembly that comprises color liquid crystal display unit and planar light source device in the one embodiment of the invention;

Fig. 6 is the concept map of a part that is applicable to the driving circuit of one embodiment of the invention;

Fig. 7 A is the synoptic diagram that the arrangement/configuration of light emitting diode in the planar light source device according to an embodiment of the invention etc. schematically is shown, and Fig. 7 B is the schematic partial cross-sectional view that comprises the liquid crystal display subassembly of color liquid crystal display unit and planar light source device according to an embodiment of the invention;

Fig. 8 is the schematic partial cross-sectional view of color liquid crystal display unit;

Fig. 9 A and 9B illustrate the wherein light source briliancy Y of surface light source unit ₂Under the control of surface light source unit driving circuit, increase or reduce so that surface light source unit obtain by hypothesis with have the maximum drive signal value x that equals in the unit, viewing area _U-maxThe control signal of drive signal correspondence of value be provided for pixel and second regulation that obtains shows the concept map of the state of brightness value y2;

Figure 10 A be value that the drive signal by will inputing to the liquid crystal display driving circuit that is used for the driven element pixel schematically the is shown value that rises curtain and obtain to 2.2 powers (x ' ≡ x ^2.2) and dutycycle (=t _ON/ t _Const) between the figure of relation, and Figure 10 B is the synoptic diagram that the value X of the control signal that is used to control the sub-pixel transmittance schematically is shown and shows the relation between the briliancy y;

Figure 11 A and 11B are the concept maps of the relation between the demonstration briliancy that illustrates in the light source briliancy of planar light source device, the transmittance of pixel (aperture ratio) and the viewing area;

Figure 12 A and Figure 12 B are respectively and the Japanese Unexamined Patent Application spy is shown opens the figure of the configuration of disclosed four light emitting diodes in the 2005-258403 communique and be illustrated in that local luminous aberration (luminous colour cast) is the figure how to take place in the outer edge area of surface light source unit;

Figure 13 A and Figure 13 B are respectively and illustrate according to the figure of the configuration of the light emitting diode in a kind of planar light source device of prior art and be schematically illustrated in that local luminous aberration (luminous colour cast) is the figure how to take place in the outer edge area of the part corresponding with surface light source unit;

Figure 14 A and Figure 14 B are respectively and illustrate according to the figure of the configuration of the light emitting diode in the another kind of planar light source device of prior art and be illustrated in that local luminous aberration (luminous colour cast) is the figure how to take place in the outer edge area with the surface light source unit counterpart.

Embodiment

Planar light source device to all embodiment according to the present invention describes below with reference to accompanying drawings.Before all embodiment are described, earlier transmission type colour liquid crystal display unit and the planar light source device that is applicable to each embodiment carried out simple declaration with reference to Fig. 5, Fig. 6 and Fig. 7 A, 7B and Fig. 8.

Shown in the concept map of Fig. 5, transmission type colour liquid crystal display unit 10 comprises a viewing area 11, comprising the M that arranges along first direction ₀Individual pixel and the N that arranges along second direction ₀The always total M of individual pixel ₀* N ₀Individual pixel is arranged in two-dimensional matrix.Here, suppose that display field district 11 is divided into P * Q unit, imaginary viewing area 12.Each unit, viewing area 12 is made of a plurality of pixels.Specifically, color liquid crystal display unit 10 has the image display resolution that for example satisfies the HD-TV standard, and as the M that arranges with the two-dimensional matrix form ₀* N ₀The number of individual pixel is represented as (M ₀, N ₀), then pixel count for example is represented as (1920,1080).In addition, the viewing area 11 (being represented by the dot-and-dash line among Fig. 5) that is made of the pixel of arranging with the two-dimensional matrix form is divided into P * Q unit, imaginary viewing area 12 (its border is represented by dotted line).(P, value Q) for example is (19,12).Yet for the purpose of simplifying accompanying drawing, the number of the unit, viewing area 12 shown in Fig. 5 (and the surface light source unit 42 that will be described later) is different with this value.Each unit, viewing area 12 is made of a plurality of (M * N) pixel, and the number that constitutes the pixel of unit, a viewing area 12 for example is about 10,000.Each pixel is made of the one group of a plurality of sub-pixel that sends different colours respectively.More particularly, each pixel is made of three sub-pixels that comprise emitting red light sub-pixel (sub-pixel [R]), green emitting sub-pixel (sub-pixel [G]) and blue-light-emitting sub-pixel (sub-pixel [B]).Transmission type colour liquid crystal display unit 10 drives line by line.More particularly, color liquid crystal display unit 10 has with matrix form scan electrode intersected with each other (they extend along first direction) and data electrode (they extend along second direction).Come scan electrode is selected and scanned by sweep signal being inputed to scan electrode, and show an image, form a screen thus based on the data-signal that inputs to data electrode (they are based on the signal of control signal).

Shown in the schematic partial cross-sectional view of Fig. 8, color liquid crystal display unit 10 comprises: the front panel 20 with first transparency electrode 24; Have the rear panel 30 of second transparency electrode 34 and be arranged on front panel 20 and rear panel 30 between liquid crystal material 13.

Front panel 20 for example comprises the polarizing coating 26 on first substrate of being made by glass substrate 21 and the outside surface that is arranged on first substrate 21.The color filter 22 that is covered with the coat 23 that is made of acryl resin or epoxy resin is set on the inside surface of first substrate 21.First transparency electrode 24 (be also referred to as public electrode, and made by for example ITO) is formed on the coat 23.Oriented layer 25 is formed on first transparency electrode 24.On the other hand, rear panel 30 for example comprises: second substrate of being made by glass substrate 31; Be formed on the on-off element 32 (specifically thin film transistor (TFT) or TFT) on second substrate, 31 inside surfaces; By second transparency electrode 34 (also be called as pixel electrode, and make) of its conducting/not conductings of on-off element 32 control and be arranged on polarizing coating 36 on the outside surface of second substrate 31 by for example ITO.Oriented layer 35 is formed on the whole surface that comprises second transparency electrode 34.Front panel 20 and rear panel 30 are engaged with each other in their outer edges separately by the sealant (not shown).Be noted that on-off element 32 is not limited to TFT.For example, on-off element 32 can be made of the MIM element.Label 37 expressions among the figure are arranged on the insulation course between per two adjacent switch elements 32.

Can constitute by known parts and material owing to constitute each parts and the liquid crystal material of transmission type colour liquid crystal display unit, therefore save its detailed description.

Directly profile light supply apparatus (backlight 40) is made of P * Q the surface light source unit 42 corresponding to P * Q unit, imaginary viewing area 12.Each surface light source unit 42 illuminates from the back side and this surface light source unit 42 corresponding display unit 12.All light sources included in the surface light source unit 42 are individually controlled.Be positioned at below the color liquid crystal display unit 10 although be noted that planar light source device 40, yet in Fig. 5, color liquid crystal display unit 10 and planar light source device 40 are illustrated respectively.Fig. 7 A schematically illustrates the configuration/arrangement of light emitting diode in the planar light source device 40 etc., and comprises the schematic partial cross-sectional view of the liquid crystal display subassembly of color liquid crystal display unit 10 and planar light source device 40 shown in Fig. 7 B.

The light source that is included in each surface light source unit 42 is made of a plurality of light-emitting device unit 43.In addition, each light-emitting device unit 43 comprises the green LED (green LED 44G specifically) of at least one red light emitting diodes that glows (red light emitting diodes 44R specifically), at least one green light and the blue LED (blue LED 44B specifically) of at least one blue light-emitting.Each

light emitting diode

44R, 44G, 44B are driven based on width modulation (PWM) control method.Be noted that red light emitting diodes 44R glows (its wavelength is for example 640nm), green LED 44G green light (its wavelength is for example 530nm), and blue LED 44B blue light-emitting (its wavelength is for example 450nm).

In addition, the shape of surface light source unit 42 is rectangle in planimetric map.

Shown in the schematic partial cross-sectional view of the liquid crystal display subassembly of Fig. 7 B, planar light source device 40 has the housing 51 that comprises housing 53 and inside casing 53.One end of transmission type colour liquid crystal display 10 is held in place to be clipped between housing 53 and the inside casing 54 by distance piece 55A, 55B.In addition, guide 56 is set between housing 53 and the inside casing 54, stops the displacement that is clipped in the color liquid crystal display unit 10 between housing 53 and the inside casing 54 thus.Top in housing 51, diffusing panel 61 is connected in inside casing 54 by distance piece 55C and cradle member 57.In addition, the optical function sheet group that comprises diffusion disk 62, prismatic lens 63 and polarisation transformation sheet 64 is laminated on the diffusing panel 61.

Reflector plate 65 is set at the bottom in the housing 51.In this case, reflector plate 65 is configured to make its reflecting surface towards diffusing panel 61, and is connected in the basal surface 52A of housing 51 via the web member (not shown).Reflector plate 65 can constitute by stack gradually the film formed silver-colored reflection enhancing coating of silver-colored reflectance coating, low refractive index film and high index of refraction on the sheet base.The light that reflector plate 65 reflection is sent from a plurality of light emitting diodes 44 or by the side 52B of housing 51 or as the case may be by the light of 41 reflections of partition wall shown in Fig. 7 A.Therefore, the ruddiness, green glow and the blue light that send from a plurality of blue LED 44B of a plurality of green LED 44G of a plurality of red light emitting diodes 44R of glowing, green light and blue light-emitting are mixed together, and can obtain the white light with high color purity as illumination light thus.This illumination light is passed through such as optical function sheet groups such as diffusion disk 62, prismatic lens 63 and polarisation transformation sheets 64, and illuminates color liquid crystal display unit 10 from the back side.

Be set near the basal surface 52A of housing 51 as

photodiode

45R, 45G, the 45B of optical sensor.It should be noted that, photodiode 45R has connected the photodiode of red filter with the light intensity of measurement ruddiness, photodiode 45G has connected the photodiode of green filter with the light intensity of measurement green glow, and photodiode 45B has connected the photodiode of blue filter with the light intensity of measurement blue light.In this case, one group of optical sensor (

photodiode

45R, 45G, 45B) is set in the surface light source unit 42.The briliancy of light emitting

diode

44R, 44G, 44B and colourity are measured by

photodiode

45R, 45G, the 45B as optical sensor.

Although be not absolute necessary, per two the adjacent surface light source cells 42 that constitute planar light source device 40 are separated each other by partition wall 41.Surface light source unit 42 surrounds by four partition walls 41 or by side 52B of three partition walls 41 and housing 51 or by two side 52B of two partition walls 41 and housing 51.

As shown in Figure 5 and Figure 6, based on comprising: backlight control unit 70 from the drive planar light source device 40 of outside (display circuit) and the driving circuit of color liquid crystal display unit 10; And the surface light source unit driving circuit 80 of conduction and cut-off control that carry out to constitute the blue LED 44B of the green LED 44G of red light emitting diodes 44R, series connection of the series connection of the light-emitting device unit 43 in each surface light source unit 42 and series connection based on pulse width modulation control method; And liquid crystal display driving circuit 90.Backlight control unit 70 comprises computing circuit 71 and storer 72.On the other hand, surface light source unit driving circuit 80 on-off element 85R, the 85G, 85B and the light emitting diode driving power (constant current source) 86 that comprise computing circuit 81, storer 82, led drive circuit 83, photodiode control circuit 84, constitute by FET.These circuit etc. that constitute backlight control unit 70 and surface light source unit driving circuit 80 can be made of known circuit etc.On the other hand, the liquid crystal display driving circuit 90 that is used to drive color liquid crystal display unit 10 is made of the known circuit such as time schedule controller 91.Liquid crystal display 10 comprises (not shown) such as the gate drivers that is used to drive the on-off element of being made by the TFT that constitutes liquid crystal cells 32, source electrode driver.Form a kind of feedback mechanism, light emitting diode 44R in the wherein given image display frame, 44G, the state of 44B is by photodiode 45R, 45G, 45B measures, from photodiode 45R, 45G, the output of 45B is input to photodiode control circuit 84, and in photodiode control circuit 84 and computing circuit 81, be converted into for example about light emitting diode 44R, 44G, the briliancy of 44B and the data of colourity (signal), these type of data are sent to led drive circuit 83, control light emitting diode 44R in next image display frame thus, 44G, the luminance of 44B.In addition, in the downstream of light emitting diode 44R, 44G, 44B, current sensing resistor r _R, r _G, r _BIn series inserted with light emitting diode 44R, 44G, 44B, flowed into resistor r _R, r _G, r _BElectric current be converted into voltage, and under the control of led drive circuit 83, the operation Be Controlled of light emitting diode driving power (constant current source) 86 is so that each resistor r _R, r _G, r _BIn voltage drop become predetermined value.Although Fig. 6 shows a light emitting diode driving power (constant current source), a plurality of light emitting diode driving powers 86 that are used to drive each light emitting diode 44R, 44G, 44B can be set in fact.

The viewing area 11 that is made of the pixel of arranging with the two-dimensional matrix form is divided into unit, P * Q viewing area.If with this state representation is " OK " and " row ", then we can say viewing area 11 be divided into Q capable * unit, viewing area of P row.In addition, unit, viewing area 12 is made of a plurality of (M * N) pixel.If with this state representation is " OK " and " row ", then we can say unit, viewing area 12 by N capable * N row pixel constitutes.Should be noted that with the two-dimensional matrix form arrange and be positioned at the capable p row of q (q=1 wherein, 2 ..., Q and p=1,2 ..., P) unit, viewing area and surface light source unit are expressed as unit, viewing area 12 separately _{(q, p)}With surface light source unit 42 _{(q, p)}, and subscript (q, p) or-(q p) then often points to and is associated with unit, viewing area 12 _{(q, p)}With surface light source unit 42 _{(q, p)}, and, subscript " (q, p) " or " (q, p) " will often be attached to and unit, viewing area 12 _{(q, p)}Or surface light source unit 42 _{(q, p)}Relevant key element or project.Here, emitting red light sub-pixel (sub-pixel [R]), green emitting sub-pixel (sub-pixel [G]) and blue-light-emitting sub-pixel (sub-pixel [B]) often are collectively referred to as " sub-pixel [R, G, B] ".Be input to sub-pixel [R, G, B] with control sub-pixel [R, G, B] the control of operation (especially for example transmittance (aperture than)) emitting red light control signal, green emitting control signal and blue-light-emitting control signal will often be collectively referred to as " control signal [R, G, B] ".Input to driving circuit from the outside to drive the sub-pixel [R that constitutes the unit, viewing area, G, B] emitting red light sub-pixel drive signals, green emitting sub-pixel drive signals and blue-light-emitting sub-pixel drive signals will be collectively referred to as " drive signal [R, G, B] ".

Each pixel comprises one group of three sub-pixel, i.e. sub-pixel [R] (emitting red light sub-pixel), sub-pixel [G] (green emitting sub-pixel) and sub-pixel [B] (blue-light-emitting sub-pixel).In following explanation to embodiment, the briliancy of each sub-pixel [R, G, B] control (gray-scale Control) be configured to from 0 to 255 2 ⁸8 controls on rank.Therefore, in constituting each pixel of each unit, viewing area 12, be input to liquid crystal display driving circuit 90 each value x with the drive signal [R, G, B] that drives each sub-pixel [R, G, B] _R, x _G, x _BGet 2 ⁸The value on rank.In addition, be used to control each value S of the pulse-width modulated output signal of the red light emitting diodes 44R, the green LED 44G that constitute each surface light source unit and the corresponding fluorescent lifetime of blue LED 44B _R, S _G, S _BAlso get from 2 of 0-255 ⁸The value on rank.Yet this should not do limited explanation.For example, control setting can be become from 2 of 0-1023 ¹⁰10 controls on rank, 8 bit digital value can increase 4 times in this case.

The control signal that is used to control the transmittance Lt of each pixel is provided for each pixel from driving circuit.Specifically, the control signal [R, G, B] of each light transmission Lt of control signal [R, G, B] that is used to control the corresponding transmittance Lt of sub-pixel [R, G, B] is provided for each sub-pixel [R, G, B].That is, in liquid crystal display driving circuit 90, control signal [R, G, B] is to generate from the drive signal of being imported [R, G, B], and control signal [R, G, B] is provided (output) to sub-pixel [R, G, B].Be noted that because the light source briliancy Y of surface light source unit 42 ₂Change with each image display frame, therefore basically, control signal [R, G, B] has separately with respect to the value that obtains to 2.2 powers by the value liter curtain with each drive signal [R, G, B], based on light source briliancy Y ₂Change carry out to proofread and correct (compensation) and the value that obtains.In addition, by known method with control signal [R, G, B] deliver to the gate drivers and the source electrode driver of color liquid crystal display unit 10 from the time schedule controller 91 that constitutes liquid crystal display driving circuit 90, drive the on-off element 32 that constitutes each sub-pixel based on control signal [R, G, B], and desired voltage is put on each first transparency electrode 24 and second transparency electrode 34 that constitutes liquid crystal cells, control the transmittance (aperture ratio) of each sub-pixel thus.In this case because the value of control signal [R, G, B] becomes bigger, so the transmittance of sub-pixel [R, G, B] (aperture of these sub-pixels than) Lt becomes higher, and the briliancy of sub-pixel [R, G, B] (showing briliancy y) becomes higher.That is, become clear by the formed image of sub-pixel [R, G, B] (being generally a kind of scattergram picture) by light.

Each image display frame, each unit, viewing area and each surface light source unit in the image demonstration of color liquid crystal display unit 10 are carried out demonstration briliancy y and light source briliancy Y ₂Control.In addition, the operation of the operation of color liquid crystal display unit 10 and planar light source device 40 is synchronized with each other in an image display frame.Be noted that the number (image of per second) that sent to the image information of driving circuit as electric signal in a second is a frame rate (frame rate), and the inverse of frame rate is frame time (unit: second).

Embodiment 1

Embodiment 1 relates to first planar light source device to the third aspect according to the present invention.

That is, in planar light source device 40, at each surface light source unit 42 according to embodiment 1 _{(q, p)}In, the basic and surface light source unit 42 of center of gravity that distributes based on the briliancy of a plurality of red light-emitting components (red light emitting diodes 44R) _{(q, p)}The center of gravity unanimity, the basic and surface light source unit 42 of center of gravity that distributes based on the briliancy of a plurality of green luminousing elements (green LED 44G) _{(q, p)}The center of gravity unanimity, and the basic and surface light source unit 42 of center of gravity that distributes based on the briliancy of a plurality of blue light emitting devices (blue LED 44B) _{(q, p)}The center of gravity unanimity.Be noted that the example that briliancy distributes is schematically illustrated in the curve map of Fig. 3.

Perhaps, in planar light source device 40, at each surface light source unit 42 according to embodiment 1 _{(q, p)}In, the basic and surface light source unit 42 of the center of gravity of the position of a plurality of red light-emitting components (red light emitting diodes 44R) _{(q, p)}The center of gravity unanimity, the basic and surface light source unit 42 of the center of gravity of the position of a plurality of green luminousing elements (green LED 44G) _{(q, p)}The center of gravity unanimity, and the center of gravity of the position of a plurality of blue light emitting device (blue LED 44B) is basic and surface light source unit 42 _{(q, p)}The center of gravity unanimity.

Note, when the characteristics of luminescence of a plurality of red light-emitting components (red light emitting diodes 44R) is identical, the basic and surface light source unit 42 of center of gravity of the center of gravity that distributes based on the briliancy of a plurality of red light-emitting components (red light emitting diodes 44R) and the position of this a plurality of red light-emitting components (red light emitting diodes 44R) _{(q, p)}The center of gravity unanimity.In addition, when the characteristics of luminescence of a plurality of green luminousing elements (green LED 44G) is identical, the basic and surface light source unit 42 of center of gravity of the center of gravity that distributes based on the briliancy of a plurality of green luminousing elements (green LED 44G) and the position of this a plurality of green luminousing elements (green LED 44G) _{(q, p)}The center of gravity unanimity.In addition, when the characteristics of luminescence of a plurality of blue light emitting devices (blue LED 44B) is identical, the basic and surface light source unit 42 of center of gravity of the center of gravity that distributes based on the briliancy of a plurality of blue light emitting devices (blue LED 44B) and the position of this a plurality of blue light emitting devices (blue LED 44B) _{(q, p)}The center of gravity unanimity.

In addition, in planar light source device 40, at each surface light source unit 42 according to embodiment 1 _{(q, p)}In, along surface light source unit 42 _{(q, p)}At least one red light-emitting component 44R, at least one green luminousing element 44G and at least one blue light emitting device 44B are set, and this red light-emitting component 44R, green luminousing element 44G and blue light emitting device 44B are along surface light source unit 42 _{(q, p)}Four limits with the same sequence setting.

More particularly, according to 1, one light source cell 42 of embodiment _{(q, p)}Comprise four light-emitting device unit 43.In addition, at a surface light source unit 42 _{(q, p)}In, each the red light-emitting component 44R that constitutes these four light-emitting device unit 43 is configured to the rotation symmetry four times, each the green luminousing element 44G that constitutes these four light-emitting device unit 43 is configured to the rotation symmetry four times, and each the blue light emitting device 44B that constitutes these four light-emitting device unit 43 is configured to the rotation symmetry four times.

That is, as shown in illustrative arrangement/arrangement of Figure 1A and 1B, each light-emitting device unit 43 comprises a red light-emitting component 44R, two green luminousing element 44G and a blue light emitting device 44B.In addition, these four light-emitting component 44R, 44G and 44B are set on four angles of hypothetical rectangle.When the hypothesis initial point is positioned at surface light source unit 42 _{(q, p)}The coordinate system of center of gravity the time, green luminousing element 44G be set at that of being arranged in the most close initial point in four jiaos of hypothetical rectangle goes up and four jiaos of hypothetical rectangle away from of initial point, and red light-emitting component 44R and blue light emitting device 44B are set at respectively on all the other two jiaos.In addition, surface light source unit 42 _{(q, p)}Four limits in red light-emitting component 44R, green luminousing element 44G and blue light emitting device 44B put in order for: when with surface light source unit 42 _{(q, p)}Center of gravity be that the center is deasil along surface light source unit 42 _{(q, p)}Four limits when moving, on all limits, light-emitting component 44R, 44G, 44B are the series arrangement of green luminousing element 44G by green luminousing element 44G, blue light emitting device 44B and red light-emitting component 44R again.Be noted that all limits of hypothetical rectangle are parallel to all limits of surface light source unit.

In addition, shown in the configuration/Pareto diagram among Figure 1B, although red light-emitting component 44R, two green luminousing element 44G and a blue light emitting device 44B are along a surface light source unit 42 _{(q, p)}One side when arranging, not with the light-emitting component of same color along a surface light source unit 42 _{(q, p)}One side be provided with adjacent to each other.In addition, when [getting surface light source unit 42 along two adjacent surface light source cells _{(q, p)}Be the center, surface light source unit 42 _{(q-1, p)}, surface light source unit 42 _{(q+1, p)}, surface light source unit 42 _{(q, p+1)+}] limit when observing, putting in order on each limit of red light-emitting component 44R, green luminousing element 44G and blue light emitting device 44B is identical.

Below in conjunction with the process flow diagram of Fig. 5 and Fig. 6 and Fig. 4 the method according to the driving liquid crystal display subassembly of embodiment 1 is described.

[step-100]

Drive signal [R, G, B] and the clock signal clk corresponding with an image display frame of sending such as the known display circuit of scan converter certainly are input to backlight control unit 70 and liquid crystal display driving circuit 90 (see figure 5)s.It should be noted that, be given as y ' if arrive the input light quantity of image pickup pipe, drive signal [R then, G, B] for example be output signal from the image pickup pipe, they are from outputs such as broadcasting stations and also be input to the transmittance Lt of liquid crystal display driving circuit 90 with the control pixel, and can be represented as the function of 0.45 power of input light quantity y '.In addition, the value x of the drive signal [R, G, B] corresponding with an image display frame that is input to backlight control unit 70 _R, x _G, x _BBe temporarily stored into the storer 72 that constitutes backlight control unit 70.In addition, the value x of the drive signal [R, G, B] corresponding with an image display frame that is input to liquid crystal display driving circuit 90 _R, x _G, x _BAlso kept in in the storer (not shown) that constitutes liquid crystal display driving circuit 90.

[step-110]

Below, in constituting the computing circuit 71 of backlight control unit 70, read the value of the drive signal [R, G, B] that is stored in the storer 72, and with respect to the (p, q) individual [wherein, p=1 at first, q=1] unit, viewing area 12 _{(q, p)}, by the maximum drive signal value x in destiny circuit 71 definite unit, viewing area _{U-max (q, p)}, (q, p) unit, individual viewing area 12 constituting the in its representative _{(q, p)}All pixels in be used for driven element pixel [R, G, B] _{(q, p)}Drive signal [R, G, B] _{(q, p)}Value x _{R-(q, p)}, x _{G-(q, p)}, x _{B-(q, p)}Central maximal value.Then, the maximum drive signal value x in the unit, viewing area _{U-max (q, p)}Be stored in the storer 72.This step be relative m=1,2 ..., M, n=1,2 ..., N all scenario, promptly carry out with respect to M * N pixel.

For example, if x _{R-(q, p)}Be value corresponding to " 110 ", x _{G-(q, p)}Be value corresponding to " 150 ", x _{G-(q, p)}Be the value corresponding to " 50 ", then x _{U-max (q, p)}It is value corresponding to " 150 ".

This operation is from (p is q)=(1,1) to (P Q) repeats, and each unit, viewing area 12 _{(q, p)}In the unit, viewing area in maximum drive signal value x _{U-max (q, p)}Be stored in the storer 72.

[step-120]

Then, so that have maximum drive signal value x in the display unit of the equaling zone separately by hypothesis _{U-max (q, p)}The drive signal [R, G, B] of value _{(q, p)}Corresponding control signal [R, G, B] _{(q, p)}Be provided for sub-pixel [R, G, B] _{(q, p)}And the briliancy that obtains (the second regulation demonstration brightness value y under the first regulation light transmittance values Lt1 _{2-(q, p)}) can be by surface light source unit 42 _{(q, p)}The mode that obtains is at surface light source unit driving circuit 80 _{(q, p)}Control under increase/reduce and unit, viewing area 12 _{(q, p)}Corresponding surface light source unit 42 _{(q, p)}Light source briliancy Y _{2-(q, p)}

Specifically, this can be by controlling light source briliancy Y to each image display frame and each surface light source unit ₂Formula (1) below satisfying realizes.More particularly, this can be by based on as light source briliancy control function g (x _Nol-max) formula (2) control light-emitting device unit 43 briliancy and control the light source briliancy Y of light-emitting device unit 43 ₂Realize to satisfy formula (1).The concept map of this control is shown in Fig. 9 A and 9B.Yet, as described later, need be according to the influence of other surface light source unit 42 grades to light source briliancy Y ₂Carry out and proofread and correct.These relation, i.e. the maximum drive signal value xs in viewing area unit relevant with the control of light source briliancy Y2 _U-max, equal this maximal value x with having _U-maxValue the drive signal correspondence control signal value, by supposing that this control signal is provided for second regulation that a pixel (sub-pixel) obtains and shows brightness value y ₂, this moment each sub-pixel transmittance (aperture than) [the second regulation light transmittance values Lt ₂], allow transmittance (aperture than) to be set at the first regulation light transmittance values Lt when each sub-pixel ₁In time, obtains relation between the briliancy controlled variable in the surface light source unit that second regulation shows brightness value y2 and can be determined in advance and be stored among the storer 72 etc.

Y ₂·Lt ₁＝Y ₁·Lt ₂ (1)

g(x _nol-max)＝a ₁·(x _nol-max) ^2.2+a ₀ (2)

Here, the maximal value of supposing to be imported into the drive signal (drive signal [R, G, B]) of the liquid crystal display driving circuit 90 that is used to drive pixel (or constitute these pixels each sub-pixel [R, G, B]) is x _Max, then have

x _nol-max≡x _0-max/x _max，

And a ₁, a ₂Be constant, and can be expressed as followsin:

a ₁+a ₀＝1

0＜a ₀＜1，0＜a ₁＜1.

For example, can be with a ₁, a ₀Be arranged to:

a ₁=0.99, and

a ₀＝0.01。

In addition, since drive signal [R, G, B] respectively be worth x _R, x _G, x _BGet the value on 28 rank, therefore be worth x _MaxIt is value corresponding to " 255 ".

Mention in passing, in planar light source device 40, suppose to control (p, surface light source unit 42 q)=(1,1) _(1,1)The situation of briliancy, then need and will take into account from the influence of other P * Q surface light source unit 42.Because these influences that act on this surface light source unit 42 from other area source 42 are found from the luminescence distribution of each surface light source unit 42 in advance, therefore can calculate difference by inverse operation, consequently can proofread and correct.To the citation form that calculate be illustrated below.

Based on formula (1) and formula (2), briliancy (the light source briliancy Y that P * Q surface light source unit 42 is required ₂) by matrix [L _{P * Q}] expression.The briliancy of the surface light source unit that obtains when in addition, in advance P * Q surface light source unit 42 being determined not drive other surface light source unit when only driving a given surface light source unit.This briliancy by matrix [L ' _{P * Q}] expression.In addition, correction coefficient is by [α _{P * Q}] expression.Then, can below formula (3-1) represent relation between these matrixes.Can determine correction coefficient matrix [α in advance _{P * Q}].

[L _P×Q]＝[L’ _P×Q]·[α _P×Q] (3-1)

Therefore, can determine according to formula (3-1) [L ' _{P * Q}].Can according to inverse matrix calculate to determine matrix [L ' _{P * Q}].Can be calculated as follows:

[L’ _P×Q]＝[L _P×Q]·[α _P×Q] ^-1 (3-2)

Then, each surface light source unit 42 of may command _{(q, p)}In included light source (a plurality of light-emitting device unit 43) with obtain by matrix [L ' _{P * Q}] expression briliancy.Specifically, can realize this operation and processing by the information (tables of data) that use is stored in the storer 82.What need not many speeches is when this a plurality of light-emitting device unit 43 of control, because matrix [L ' _{P * Q}] value can not get negative value, therefore be necessary result of calculation is remained in the positive scope.Therefore may exist separating of formula (3-2) not to be exact solution but the situation of approximate solution.

In this way, the matrix [L that obtains on the basis based on the value of the formula (1) that obtains at the computing circuit 71 that constitutes backlight control unit 70 and (2) _{P * Q}] and the matrix [α of correction coefficient _{P * Q}], definite in the above described manner briliancy matrix that obtains by hypothesis individual drive surface light source unit [L ' _{P * Q}], become a corresponding integer in 1 to 255 scope based on being stored in translation table in the storer 72 then.In this way, in the computing circuit 71 that constitutes backlight control unit 70, can obtain to be used for chain of command light source cell 42 _{(q, p)}In the value S of pulse-width modulated output signal of fluorescent lifetime of red light emitting diodes 44R _{R-(q, p)}, be used to control the value S of pulse-width modulated output signal of the fluorescent lifetime of green LED 44G _{G-(q, p)}, and the value S of pulse-width modulated output signal that is used to control the fluorescent lifetime of blue LED 44B _{B-(q, p)}

[step 130]

Next, the value S of the pulse-width modulated output signal that in the computing circuit 71 that constitutes backlight control unit 70, obtains _{R-(q, p)}, S _{G-(q, p)}, S _{B-(q, p)}Be sent to corresponding to surface light source unit 42 _{(q, p)}The surface light source unit driving circuit 80 that is provided with _{(q, p)} Storer 82, and be stored in the storer 82.In addition, clock signal clk also is sent to surface light source unit driving circuit 80 _{(q, p)}(see figure 6).

[step 140]

Then, based on the value S of pulse-width modulated output signal _{R-(q, p)}, S _{G-(q, p)}, S _{B-(q, p)}, computing circuit 81 determines to constitute area source case source 42 _{(q, p)}The ON time t of red light emitting diodes 44R _R-ONWith t closing time _R-OFF, green LED 44G ON time t _G-ONWith t closing time _G-OFF, and the ON time t of blue LED 44B _B-ONWith t closing time _B-OFF

Note

t _R-ON+ t _R-OFF=t _G-ON+ t _G-OFF=t _B-ON+ t _B-OFF=constant t _Const

In addition, can be represented as based on the dutycycle in the driving of the width modulation of light emitting diode:

t _ON/(t _ON+t _OFF)＝t _ON/t _Const.

In addition, with formation surface light source unit 42 _{(q, p)}Red light emitting diodes 44R, green emitting divalence pipe 44G and the ON time t of blue LED 44B _{R-ON-(q, p)}, t _{G-ON-(q, p)}, t _{B-ON-(q, p)}Corresponding signal is sent to led drive circuit 83, and based on ON time t _{R-ON-(q, p)}, t _{G-ON-(q, p)}, t _{B-ON-(q, p)}The value of corresponding signal, on-off

element

85R _{(q, p)}, 85G _{(q, p)}, 85B _{(q, p)}At ON time t _{R-ON-(q, p)}, t _{G-ON-(q, p)}, t _{B-ON-(q, p)}Interior by led drive circuit 83 conductings, the LED drive current from light emitting diode driving power 86 is reached each

light emitting diode

44R, 44G and 44B thus.As a result, in an image display frame, each

light emitting diode

44R, 44G, 44B are at ON time t _{R-ON-(q, p)}, t _{G-ON-(q, p)}, t _{B-ON-(q, p)}In luminous, (p, q) unit, individual viewing area 12 thereby illuminate the with predetermined briliancy _{(q, p)}

So the state that obtains is represented by the solid line among Figure 10 A and the 10B.Figure 10 A schematically illustrates dutycycle (=t _ON/ t _Const) with the value of drive signal by will inputing to liquid crystal display driving circuit 90 rise the value that curtain to 2.2 powers obtain (x ' ≡ x ^2.2) between the synoptic diagram of relation.Figure 10 B schematically illustrates to show briliancy y and be used to control the figure that concerns between the value X of control signal of sub-pixel transmittance Lt.

[step-150]

On the other hand, be input to the drive signal [R, G, B] of liquid crystal display driving circuit 90 _{(q, p)}Value x _{R-(q, p)}, x _{G-(q, p)}, x _{B-(q, p)}Be sent to time schedule controller 91, and with the drive signal of being imported [R, G, B] _{(q, p)}Corresponding control signal [R, G, B] _{(q, p)}Be provided (output) to sub-pixel [R, G, B] _{(q, p)}Offer sub-pixel [R, G, B] by time schedule controller 91 generations of liquid crystal display driving circuit 90 and from liquid crystal display driving circuit 90 _{(q, p)}Control signal [R, G, B] _{(q, p)}Value x _{R-(q, p)}, x _{G-(q, p)}, x _{B-(q, p)}, and drive signal [R, G, B] _{(q, p)}Value x _{R-(q, p)}, x _{G-(q, p)}, x _{B-(q, p)}Has relation, wherein b by formula (4-1), formula (4-2), formula (4-3) expression _{1_R}, b _{0_R}, b _{1_G}, b _{0_G}, b _{1_B}, b _{0_B}It is constant.Should be noted that because surface light source unit 42 _{(q, p)}Light source briliancy Y _{2-(q, p)}Change along with each image display frame, therefore basically, all control signals [R, G, B] _{(q, p)}Have separately based on light source degree of painting Y _{2-(q, p)}Change to by with each drive signal [R, G, B] _{(q, p)}Value separately rises curtain to the value of 2.2 powers acquisition and proofreaies and correct the value that (compensation) mode obtains.That is, in embodiment 1, because light-source brightness Y _{2-(q, p)}Along with each image display frame changes, therefore determine and correction (compensation) control signal [R, G, B] _{(q, p)}Value x _{R-(q, p)}, x _{G-(q, p)}, x _{B-(q, p)}With at light source briliancy Y _{2-(q, p)}(≤Y ₁) the following second regulation demonstration brightness value y that obtains _{2-(q, p)}, control transmittance (aperture than) Lt of pixel or sub-pixel thus.Here, the function f in formula (4-1), formula (4-2), the formula (4-3) _R, f _G, f _BIt is the pre-determined function that this class is proofreaied and correct (compensation) that is used for carrying out.

X _R-(q，p)＝f _R(b _{1_R}·x _R-(q，p) ²²+b _{0_R}) (4-1)

X _G-(q，p)＝f _G(b _{1_G}·x _G-(q，p) ²²+b _{0_G}) (4-2)

X _B-(q，p)＝f _B(b _{1_B}·x _B-(q，p) ²²+b _{0_B}) (4-3)

In this way, the image display operations in image display frame has just been finished.

Embodiment 2

Embodiment 2 is distortion of embodiment 1.Shown in illustrative arrangement/arrangement of Fig. 2 A and 2B, in embodiment 2, each light-emitting device unit 43 comprises a red light-emitting component (red light emitting diodes 44R), a green luminousing element (green LED 44G) and a blue light emitting device (blue LED 44B).In addition, these three light-emitting

component

44R, 44B, 44B are separately positioned on the distal portions of the straight thick stick of imagination letter " L ", the distal portions of its whippletree and the intersection point place of straight thick stick and whippletree.Should be noted that the straight thick stick of imaginary letter " L " and all limits that whippletree is parallel to surface light source unit, and the intersection point of the Zhi Gang of imagination letter " L " and horizontal stroke is near the bight of surface light source unit.

In addition, surface light source unit 42 _{(q, p)}Four limits in red light-emitting component 44R, green luminousing element 44G and putting in order of blue light emitting device 44B be: when with surface light source unit 42 _{(q, p)}Center of gravity be that the center is along surface light source unit 42 _{(q, p)}Four limits clockwise when mobile, on all limits, light-emitting

component

44R, 44G, 44R are the series arrangement of green luminousing element 44G with green luminousing element 44G, blue light emitting device 44B and red light-emitting component 44R again.

In addition, shown in illustrative arrangement/arrangement of Fig. 2 B, although along surface light source unit 42 _{(q, p)}One side a red light-emitting component 44R, a green luminousing element 44G and a blue light emitting device 44B are set, yet not along a surface light source unit 42 _{(q, p)}One side the light-emitting component of same color is set adjacent to each other.In addition, when when the limit of two adjacent surface light source units is observed, [getting surface light source unit 42 _{(q, p)}Be the center, surface light source unit 42 _{(q-1, p)}, surface light source unit 42 _{(q+1, p)}, surface light source unit 42 _{(q, p+1)}], putting in order on each limit of red light-emitting component 44R, green luminousing element 44G and blue light emitting device 44B is identical.

Except the arrangement of above-mentioned light emitting diode, identical with configuration, structure, operation and driving method according to embodiment 1 according to configuration, structure, operation and the driving method of embodiment 2.Therefore omit its detailed description.

Although describe the present invention by preferred embodiment, but the present invention is not limited to these embodiment, the configuration of the transmission type colour liquid crystal display unit shown in all embodiment, planar light source device, surface light source unit, liquid crystal display subassembly and driving circuit and structure and their parts and material only are exemplary, and can suitably revise.Although in all embodiment, each light-emitting device unit is set on four jiaos of surface light source unit, yet the configuration of each light-emitting device unit is not limited to this.Each light-emitting device unit also can be positioned adjacent to four limits of surface light source unit.Also can pass through the temperature of temperature sensor monitors light emitting diode, and will monitor that the result feeds back to surface light source unit driving circuit 80, carry out the briliancy compensation (correction) or the temperature control of surface light source unit 42 thus.Although the viewing area that above explanation to all embodiment is based on liquid crystal display is divided into the hypothesis of P * Q unit, imaginary viewing area, yet according to practical situation, the transmission-type liquid crystal display unit can have the structure that viewing area wherein is divided into P * Q actual displayed territory element.

Although in the above-described embodiments, explanation be at satisfy constitutive characteristic according to the planar light source device of first aspect present invention, at according to the constitutive characteristic of the planar light source device of second aspect present invention and according to the planar light source device of the constitutive characteristic of the planar light source device of third aspect present invention, yet this planar light source device can:

(1) only satisfies constitutive characteristic according to the planar light source device of first aspect present invention;

(2) only satisfy constitutive characteristic according to the planar light source device of second aspect present invention;

(3) only satisfy constitutive characteristic according to the planar light source device of third aspect present invention;

(4) satisfy according to the constitutive characteristic of the planar light source device of first aspect present invention and according to the constitutive characteristic of the planar light source device of second aspect present invention;

(5) satisfy according to the constitutive characteristic of the planar light source device of second aspect present invention and according to the constitutive characteristic of the planar light source device of third aspect present invention;

(6) satisfy according to the constitutive characteristic of the planar light source device of third aspect present invention and according to the constitutive characteristic of the planar light source device of first aspect present invention.

Claims

1. a planar light source device illuminates the transmission-type liquid crystal display unit from the back side, and described liquid crystal display has the viewing area that comprises the pixel of arranging with two-dimensional matrix, and described planar light source device comprises:

P * Q surface light source unit, P * Q the unit, imaginary viewing area that P * Q unit, imaginary viewing area obtains is corresponding with being divided into by the viewing area of supposing described liquid crystal display,

Wherein,

Light source included in the described surface light source unit is individually controlled,

Included light source comprises a plurality of light-emitting device unit in each described surface light source unit,

Each described light-emitting device unit comprises the green luminousing element of at least one red light-emitting component that glows, at least one green light, and the blue light emitting device of at least one blue light-emitting,

The center of gravity that distributes based on the briliancy of a plurality of red light-emitting components in each described surface light source unit is basic consistent with the center of gravity of described surface light source unit,

The center of gravity that distributes based on the briliancy of a plurality of green luminousing elements in each described surface light source unit is basic consistent with the center of gravity of described surface light source unit, and

The center of gravity that distributes based on the briliancy of a plurality of blue light emitting devices in each described surface light source unit is basic consistent with the center of gravity of described surface light source unit.

2. a planar light source device illuminates the transmission-type liquid crystal display unit from the back side, and described liquid crystal display has the viewing area that comprises the pixel of arranging with two-dimensional matrix, and described planar light source device comprises:

Wherein,

The center of gravity of the position of a plurality of red light-emitting components in each described surface light source unit is basic consistent with the center of gravity of described surface light source unit,

The center of gravity of the position of a plurality of green luminousing elements in each described surface light source unit is basic consistent with the center of gravity of described surface light source unit, and

The center of gravity of the position of a plurality of blue light emitting devices in each described surface light source unit is basic consistent with the center of gravity of described surface light source unit.

3. a planar light source device illuminates the transmission-type liquid crystal display unit from the back side, and described liquid crystal display has the viewing area that comprises the pixel of arranging with two-dimensional matrix, and described planar light source device comprises:

Wherein,

Described surface light source unit is rectangle in planimetric map,

In each described surface light source unit, each limit along described surface light source unit is provided with at least one red light-emitting component, at least one green luminousing element, and at least one blue light emitting device, and described red light-emitting component, described green luminousing element and described blue light emitting device are arranged with same sequence along four limits of described surface light source unit.

4. as any one described planar light source device in the claim 1 to 3, it is characterized in that each described surface light source unit comprises four light-emitting device unit.

5. planar light source device as claimed in claim 4, it is characterized in that, in each described surface light source unit, each red light-emitting component that constitutes described four light-emitting device unit is provided with symmetrically by four rotations, each green luminousing element that constitutes described four light-emitting device unit is provided with symmetrically by four rotations, and each blue light emitting device that constitutes described four light-emitting device unit is provided with symmetrically by four rotations.

6. planar light source device as claimed in claim 5 is characterized in that:

Each described light-emitting device unit comprises a red light-emitting component, two green luminousing elements and a blue light emitting device;

Described four light-emitting components are set on four jiaos of hypothetical rectangle; And

When the hypothesis initial point is positioned at described on planimetric map during the coordinate system on the center of gravity of rectangular surface light source unit, described two green luminousing elements be set at respectively be arranged in described hypothetical rectangle four jiaos one of the most close described initial point and described hypothetical rectangle four jiaos away from a place of described initial point, and described red light-emitting component and described blue light emitting device are separately positioned on remaining two jiaos places.

7. planar light source device as claimed in claim 5 is characterized in that:

Each described light-emitting device unit comprises a red light-emitting component, a green luminousing element, and a blue light emitting device, and

Described three light-emitting components are set at the distal portions of the whippletree of the distal portions of the straight thick stick of an imagination letter " L ", described imaginary alphabetical " L " respectively, and the intersection point place between described straight thick stick and the described whippletree.

8. a transmission-type liquid crystal display unit has the viewing area that comprises the pixel of arranging with two-dimensional matrix, comprises the planar light source device that illuminates described liquid crystal display from the back side,

Wherein:

Described planar light source device comprises and is divided into P * Q P * Q the corresponding surface light source unit of unit, imaginary viewing area that P * Q unit, imaginary viewing area obtains by the viewing area of supposing described liquid crystal display;

Light source included in the described surface light source unit is individually controlled;

Included light source comprises a plurality of light-emitting device unit in each described surface light source unit;

Each described light-emitting device unit comprises the green luminousing element of at least one red light-emitting component that glows, at least one green light, and the blue light emitting device of at least one blue light-emitting;

9. a transmission-type liquid crystal display unit has the viewing area that comprises the pixel of arranging with two-dimensional matrix, comprises the planar light source device that illuminates described liquid crystal display from the back side,

Wherein: